CN102185304A - Surge protection circuit of video input signal - Google Patents
Surge protection circuit of video input signal Download PDFInfo
- Publication number
- CN102185304A CN102185304A CN201110124538XA CN201110124538A CN102185304A CN 102185304 A CN102185304 A CN 102185304A CN 201110124538X A CN201110124538X A CN 201110124538XA CN 201110124538 A CN201110124538 A CN 201110124538A CN 102185304 A CN102185304 A CN 102185304A
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- resistance
- discharge tube
- video input
- video
- protection circuit
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Abstract
The invention discloses a surge protection circuit of a video input signal, comprising a capacitor C1, a discharge tube T1 and three resistors R1, R2 and R3, wherein the resistor R1, the resistor R3 and the coupling capacitor C1 are connected to a video input circuit in series; one end of the discharge tube T1 is connected with a video input line at the front end of the resistor R1, and the other end of the discharge tube T1 is grounded; and one end of the resistor R2 is connected with the back end of the resistor R1 and the other end of the resistor R2 is grounded. The surge protection circuit can protect video AD devices at the same time of not influencing signal quality and avoids the devices from being burnt due to surge impact. The surge protection circuit is provided with one discharge tube and four capacitance resistance elements, and the structure is simple.
Description
Technical field
The present invention relates to a kind of circuit, relate in particular to a kind of video AD device that can effectively protect the rear end, avoid being damaged the surge protection circuit of video input signals by surge.
Background technology
At present, known video input signals surge protection circuit is to increase a discharge tube over the ground on incoming line, and the as close as possible external interface of discharge tube position is before impedance matching resistance.When a surging signal occurring on the video incoming line; surging signal voltage is 2000～4000V; duration 10～70us; and the discharge tube conducting voltage is 10～150V; surge voltage is far above the discharge tube conducting voltage; discharge tube conducting discharge is rushed down most of electric current on the ground, has protected the video AD device of rear end.But,, use foregoing circuit can not play the surge protection effect at present at the TW28xx series video AD device of a large amount of TechWell that use of field of video monitoring.When discharge tube conducting cascading water, have the part electric current to arrive the video AD device, actual test finds, when surge voltage greater than 200V, can burn device, far can not reach the surge requirement of shelter of GB GB/T 17626.5.Therefore press for a kind of new protective circuit of research and development and prevent surge impact.
Summary of the invention
Can not effectively protect the deficiency of the above surge impact of video AD device opposing 2000V in order to overcome existing circuit; the invention provides a kind of surge protection circuit of video input signals; this protective circuit is under the situation that does not influence video signal quality; the surge protective capacities is brought up to 4500V from 200V, surpass the standard of GB peak demand 4000V.
The technical solution adopted for the present invention to solve the technical problems is: a kind of surge protection circuit of video input signals, it comprises capacitor C 1, discharge tube T1 and three resistance R 1～R3.Wherein, described resistance R 1, resistance R 3, coupling capacitance C1 are connected on the video input circuit successively, and discharge tube T1 one end links to each other with the video incoming line of resistance R 1 front end, other end ground connection, and resistance R 2 one ends link to each other other end ground connection with resistance R 1 rear end.
The invention has the beneficial effects as follows; the surge protection circuit of video input signals of the present invention can have been protected the video AD device simultaneously not influencing signal quality, has avoided surge impact to cause device to burn, and this protective circuit is except that 1 discharge tube; only 4 Resistor-Capacitor Units are simple in structure.
Description of drawings
Fig. 1 is circuit theory diagrams of the present invention.
Embodiment
The present invention increases a discharge tube over the ground on the video incoming line, be positioned at before the impedance matching resistance, and after impedance matching electric resistance partial pressure point, increase a current-limiting resistance again, the choice of location of this current-limiting resistance is very crucial, must be placed on the impedance matching that does not just influence circuit after the dividing point, utilize the characteristic of video AD device high input impedance simultaneously, restriction electric current and do not influence signal quality.The video AD device is burnt not to be because high voltage but big electric current, and when surging signal arrived, current-limiting resistance was very low scope of electric current restriction, and the discharge tube of most electric current by front end bleeds off, thereby has reached the purpose of protecting the video AD device.
Further specify the present invention below in conjunction with accompanying drawing, it is more obvious that purpose of the present invention and effect will become.
As shown in Figure 1, the surge protection circuit of video input signals of the present invention comprises capacitor C 1, discharge tube T1 and three resistance R 1～R3.Wherein, resistance R 1, resistance R 3, coupling capacitance C1 are connected on the video input circuit successively, discharge tube T1 one end links to each other with the video incoming line of resistance R 1 front end, other end ground connection, resistance R 2 one ends link to each other other end ground connection with resistance R 1 rear end, resistance R 1, resistance R 2 constitute the line impedance match circuit, usually resistance R 1 is 75 ohm with resistance R 2 resistance sums, and resistance R 3 is a current-limiting resistance, must be connected to the rear of R1 and R2 tie point.Usually the current-limiting resistance resistance is tens to several kilo-ohms.
With protected video AD device is that TW2864 is an example, and R1 selects 0 ohm, and R2 selects 75 ohm, and 1000 ohm of R3 selections are proper, and after tested, the surge protective capacities can reach 4500V.
Claims (1)
1. the surge protection circuit of a video input signals is characterized in that, it comprises capacitor C 1, discharge tube T1 and three resistance R 1～R3 etc.; Wherein, described resistance R 1, resistance R 3, coupling capacitance C1 are connected on the video input circuit successively, and discharge tube T1 one end links to each other with the video incoming line of resistance R 1 front end, other end ground connection, and resistance R 2 one ends link to each other other end ground connection with resistance R 1 rear end.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201110124538XA CN102185304A (en) | 2011-05-16 | 2011-05-16 | Surge protection circuit of video input signal |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201110124538XA CN102185304A (en) | 2011-05-16 | 2011-05-16 | Surge protection circuit of video input signal |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN102185304A true CN102185304A (en) | 2011-09-14 |
Family
ID=44571397
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201110124538XA Pending CN102185304A (en) | 2011-05-16 | 2011-05-16 | Surge protection circuit of video input signal |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN102185304A (en) |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1053868A (en) * | 1990-01-30 | 1991-08-14 | 雷伊化学有限公司 | Circuit protection device |
| US6330138B1 (en) * | 1998-06-12 | 2001-12-11 | Samsung Electronics Co., Ltd. | Impedance matching circuit |
| CN1674390A (en) * | 2005-03-11 | 2005-09-28 | 广东中钰科技有限公司 | Lightning protection device for video frequency monitoring equipment |
| US20080062606A1 (en) * | 2006-03-15 | 2008-03-13 | Brown Kenneth J | Surge protection device for coaxial cable with diagnostic capabilities |
| CN101247042A (en) * | 2007-02-14 | 2008-08-20 | 浙江大华技术股份有限公司 | Video protection circuit |
| CN202084921U (en) * | 2011-05-16 | 2011-12-21 | 浙江大华技术股份有限公司 | Surge protection circuit of video input signal |
-
2011
- 2011-05-16 CN CN201110124538XA patent/CN102185304A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1053868A (en) * | 1990-01-30 | 1991-08-14 | 雷伊化学有限公司 | Circuit protection device |
| US6330138B1 (en) * | 1998-06-12 | 2001-12-11 | Samsung Electronics Co., Ltd. | Impedance matching circuit |
| CN1674390A (en) * | 2005-03-11 | 2005-09-28 | 广东中钰科技有限公司 | Lightning protection device for video frequency monitoring equipment |
| US20080062606A1 (en) * | 2006-03-15 | 2008-03-13 | Brown Kenneth J | Surge protection device for coaxial cable with diagnostic capabilities |
| CN101247042A (en) * | 2007-02-14 | 2008-08-20 | 浙江大华技术股份有限公司 | Video protection circuit |
| CN202084921U (en) * | 2011-05-16 | 2011-12-21 | 浙江大华技术股份有限公司 | Surge protection circuit of video input signal |
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| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C12 | Rejection of a patent application after its publication | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20110914 |